[LUM#13] The Bat Under the Radar
Gaining a better understanding of the coronaviruses found in bats to better prevent, anticipate, and respond to a potential new zoonotic disease. That is the goal of the project led by virologist Martine Peeters. Here’s an explanation.
What do COVID-19, rabies, and Ebola have in common? “For each of these diseases, the natural reservoir of the virus is the bat,” explains Martine Peeters. “When we trace the origins of an emerging infectious disease, we very often come across this small mammal, ” adds the virologist from the Translational Research on HIV and Infectious Diseases Laboratory*. But why bats? “They account for 20% of the world’s mammals, so when we look for the origin of a zoonosis, there’s a one-in-five chance it’s a bat, ” explains the researcher.
Flying viral reservoirs
Found on every continent—except Antarctica—these countless bats are veritable flying viral reservoirs. Thousands of viruses have been identified in bats, belonging to 28 distinct viral families. Among them is the coronavirus family. “Most of the time, infection with these viruses is asymptomatic in bats, so the animal won’t die from the disease and can thus spread the virus more effectively,” explains Martine Peeters. And, as the only flying mammal, the bat can move quickly and over long distances. “There is therefore a greater risk that they will transmit the viruses they carry to other species.” Including humans.
“Within the coronavirus family alone, seven viruses have already been identified that have jumped from bats to humans.” While four cause simple colds, the other three are responsible for Middle East Respiratory Syndrome (MERS-CoV) and severe acute respiratory syndromes caused by SARS-CoV-1 and SARS-CoV-2, the infamous coronavirus responsible for the COVID-19 pandemic. How did these viruses make the leap from bats to humans? “This cross-species transmission can occur via an intermediate host or directly, ” explains Martine Peeters. Contact between humans and bats is indeed very frequent: “Bats are hunted for food or to make traditional remedies; children play with these animals; their guano is used for crops; fruits consumed by humans are sometimes contaminated by bat saliva, urine, or feces…,” explains the virologist. And the destruction of bats’ natural habitat only increases the risk of cross-species transmission (read the article “If we don’t change, it will happen again”).
10,000 bats
This list of the seven coronaviruses that have already jumped to humans is therefore likely to grow in the near future. “To prepare for this possibility, it is important to better understand the diversity of coronaviruses circulating among bats, ” explains Martine Peeters. Together with Guinean researcher Alpha Keita, the virologist aims to document the prevalence, genetic diversity, and geographic distribution of coronaviruses in wild bats in Africa. The goal: to assess the risk of future zoonotic transmissions.
Researchers already have blood, saliva, and fecal samples collected in Guinea, Cameroon, and the Democratic Republic of the Congo from more than 10,000 bats. Thanks to this new project, they will be able to screen these samples to study the presence of viral RNA or antibodies against coronaviruses and thus estimate their prevalence. Another objective is to study the seasonality of these viruses. “If certain coronaviruses exhibit seasonal patterns, we might not detect them in one-off samples. But since we conducted monthly monitoring over the course of a year, we’ll be able to check for the presence of viruses in every sample and determine any seasonal patterns.”
Reduce the risk of transmission
This is valuable information for researchers: “If there is a seasonal pattern, we will be able to identify the times when viral shedding is highest and thus determine the period of greatest risk for zoonotic transmission, ” explains the virologist. This more detailed understanding of coronaviruses found in bats would thus help reduce the risk of transmission, but also enable faster identification of the causative agent in the event of a new zoonotic disease , “particularly through targeted diagnostic tools.” And if such an epidemic scenario were to recur, the results of this groundbreaking project would offer hope for the faster development of a treatment or vaccine. “For example, we could work on developing a broad-spectrum vaccine. We’ll also have a better understanding of the targets for antiviral drugs that could be effective against these coronaviruses, enabling us to identify or develop effective treatments.”
Tools that everyone hopes they won’t need, however. “The key to limiting the risk of a new zoonotic disease is still to limit contact between humans and the wild.” If everyone stays home, the coronaviruses will be kept at bay.
UM podcasts are now available on your favorite platform (Spotify, Deezer, Apple Podcasts, Amazon Music, etc.).
* UMR TransVIHMI (University of Marseille, IRD, INSERM U1175, Check Anta Diop University (Dakar, Senegal), University of Yaoundé 1 (Cameroon))